1. Field of the Invention
The present invention relates to improvements made in control devices for valves of the type in which the drive shaft of the stopper is controlled in one direction by an operating lever, and in the other direction by the release of a spiral spring. 2. Discussion of Background Material
A device which illustrates the state of the art is described in French published application No. 2,640,024. In such a device, the spiral spring is enclosed in a casing constituted of two portions, fixed on the body of the valve, one of the ends of the springs being fixed to the shaft driven by the operating lever, and the other being fixed to the casing.
Experience has shown with such a device that the opening and closing operations are too quick. It has also been noted, in particular, that during closing, under the action of the spring, shocks are capable of bringing about detrimental results.